**4. Conclusion**

as fertilizer and/or stimulator. This requires special care, mainly because of the risk of contamination with heavy metals, fact unwanted for the crops. The use of these residues should occur only with the removal of these contaminants or with the purification of the silicon source. The

Some plants, like the dicotyledons, do not accumulate this nutrient on the tissues. But, in the other hand, sugar cane and other grasses have ease of absorption and accumulation of Si (**Figure 6**). The effects of biostimulants are a result from deposition within the tissues, specifically in the cell wall which increases the thickness, stiffness and lignification of cells. This confers better resistance to biotic and abiotic stresses. They are also physical benefits to the barriers of silica on the fabrics, giving best architecture to plants with leaves more upright and reducing shading which improves photosynthetic efficiency, since there is a reduction in the rates of transpiration. Lower transpiration implies less demand of water by plants and reduction in levels of damage caused by fungi and insects phytophagous Lepidoptera. In another analysis [31], the plants are submitted to several physiological and metabolic diseases. There are many other discoveries that show interference in the activity of some enzymes, reducing the antioxidant capacity of some oxidative compounds, interfering in relations of water in the plant, photosynthesis, absorption of nutrients, mobility of ions inside of the plant tissues, hormone balance and in gene expression. It reports that Si increases the concentration of some metabolites nonenzy-

The use of fertilization facilitates the action of the plant to regulate the nutritional balance. Besides the ability to regulate the absorption of Zn in the presence of high levels of P, can be prevented the onset of symptoms of deficiency of Mn and B; reduces the absorption of Na in plants exposed to high concentrations; reduces the toxicity of heavy metals and Al forming a link themselves metal. From the physiological point of view, there is a great efficiency of Si in avoiding or reducing the permeability and selectivity of the plasmatic membrane at the input and output of ions under

**Figure 6.** Transverse cuttings of leaf blade limb of rice plants (Oryza sativa L.). (A) Detail showing projection of the external wall of the epidermis on the adaxial side (×1000) of the leaf limb treated with 5 mg of N and zero of SiO2

(B) Detail showing projection of the external wall of the epidermis on the adaxial side (×1000) of the leaf limb treated with

(×400). The tip of the arrow at B indicates spherical silica bodies. Source: Mauad et al. [30].

other problem is the very low mobility in the phloem of plants.

202 Sugarcane - Technology and Research

matic acting and defensively against oxidizing agents.

5 mg of N and 400 mg of SiO2

The proper nutrition of sugarcane is very important to obtain high production of the crop. With the use of organo-mineral biostimulants and fertilizers in association, the global importance of the improvement of this technology stands out. The productivity gains in sugarcane plantations are notorious. The big gains come from building and maintaining a fertile soil to the cycling of essential nutrients that are discarded as trash. There is, also, a reduction of the contamination of fountains and subsoil, reduction of the emission of gases that cause greenhouse effect, and reduction of proliferating environments of diseases and their respective vectors.

The environmental, economic and social gains are great when this agricultural practice in the cultivation of sugarcane is used. The emergence and use of new technologies are ways to achieve greater productivity, sustainability and profitability. Several technologies on the use of plant hormones, especially synthetic ones, have contributed to these goals.
